Flower-like Cobalt Hydroxide/Oxide on Graphitic Carbon Nitride for Visible-Light-Driven Water Oxidation

Abstract

Direct water oxidation via photocatalysis is a four-electron and multiple-proton process which requires high extra energy input to produce free dioxygen gas, making it exacting, especially under visible light irradiation. To improve the oxygen evolution reaction rates (OERs) and utilize more visible light, flower-like cobalt hydroxide/oxide (Fw-Co(OH)/Fw-CoO) photocatalysts were prepared and loaded onto graphitic carbon nitride (g-CN) by a facile coating method in this work. Influenced by the unique three-dimensional morphologies, the synthesized Fw-Co(OH) or Fw-CoO/g-CN hybrids reveal favorable combination and synergism reflected by the modified photoelectric activities and the improved OER performances. Attributed to its prominent hydrotalcite structure, Fw-Co(OH) shows better cocatalytic activity for g-CN modification compared with that of Fw-CoO. Specifically, 7 wt % Fw-Co(OH)/g-CN photocatalyst exhibits photocurrent density 4 times higher and OER performance 5 times better than pristine g-CN. This work unambiguously promotes the application of sustainable g-CN in water oxidation.

Ultrasmall Co@Co(OH)2 Nanoclusters Embedded in N‐Enriched Mesoporous Carbon Networks as Efficient Electrocatalysts for Water Oxidation

“…Similarly, a set of peaks in the core‐level spectrum of C 1s reveals the presence of sp 2 ‐hybridized carbon C=C (284.2 eV), C=N−C (285.7 eV), and C−O/C=O (288.2 eV; Figure c). The N 1s core‐level spectrum was also deconvoluted into a set of four peaks corresponding to C−N=C (398.3 eV; triazine network), N−(C) 3 (399.6 eV; tertiary N), C−N−H (400.9 eV; pyrrolic‐type N), and a shake‐up satellite peak (402.3 eV), as presented in Figure d . The higher intensity of tertiary N indicates the presence of a considerable amount of heptazine units present in the whole structure.…”

“…The N1score-level spectrum was also deconvoluted into as et of four peaks corresponding to CÀN=C (398.3 eV;t riazine network), NÀ(C) 3 (399.6 eV;t ertiary N),C ÀNÀ H( 400.9 eV;p yrrolic-type N), andashake-up satellite peak (402.3 eV), as presented in Figure 3d. [31] The higher intensity of tertiaryNindicates the presence of ac onsiderable amount of heptazine units present in the whole structure. Furthermore, both EDX analysis ( Figure 1e…”

Heterostructured WO3@CoWO4 bilayer nanosheets for enhanced visible-light photo, electro and photoelectro-chemical oxidation of water

“…Interestingly, active seven-line paramagnetic signals were captured as cDMPO-X under irradiation aer adding WO 3 or WO 3 @CoWO 4 -3, which might arise from the excessive oxidation of DMPO by the peroxide generated during the OER. [34][35][36] In general, the water oxidation reaction proceeds via fourelectron-transfer steps based on the following mechanism: 27 Step 1 * + H 2 O / *OH + H + + e À…”

Engineering Reusable Sponge of Cobalt Heterostructures for Highly Efficient Organic Pollutants Degradation via Peroxymonosulfate Activation

“…However, such powder‐type design usually not feasible for practical applications due to limited surface area and poor stability of the Co 3 O 4 catalyst, as well as and the inconvenience associated with the recovery of the catalyst. To address this issue, a variety of new designs have been proposed to produce porous Co 3 O 4 with different morphologies ( e. g ., nano‐spheres, rings, rods, cubes, hollow spheres, and flowers) . Improved oxidative performances were reported, mainly due to the increased surface area of the catalysts and enhanced mass transport.…”